From 0ddd676ef04a72d89c0fa734aeca0596841874e4 Mon Sep 17 00:00:00 2001
From: Remo Rechkemmer <59358383+monacoremo@users.noreply.github.com>
Date: Sun, 7 Feb 2021 22:15:44 +0100
Subject: [PATCH] nix: Add a script to generate a graph of Haskell imports
 (#1751)

---
 .gitignore       |  1 +
 nix/devtools.nix | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/.gitignore b/.gitignore
index d00cdb788..d6f521cb7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,3 +21,4 @@ __pycache__
 *.tix
 coverage
 .hpc
+imports.png
diff --git a/nix/devtools.nix b/nix/devtools.nix
index f272bfb24..b3a0bc6cb 100644
--- a/nix/devtools.nix
+++ b/nix/devtools.nix
@@ -3,6 +3,7 @@
 , checkedShellScript
 , devCabalOptions
 , entr
+, graphviz
 , silver-searcher
 , style
 , tests
@@ -96,6 +97,41 @@ let
         ${style}/bin/postgrest-lint
         ${style}/bin/postgrest-style-check
       '';
+
+  importsgraph =
+    checkedShellScript
+      {
+        name = "postgrest-importsgraph";
+        docs =
+          ''
+            Render the imports between PostgREST modules as a graph.
+
+            Output is written to 'imports.png' in the root directory of the project.
+          '';
+        inRootDir = true;
+      }
+      ''
+        imports=$(
+          grep -rE 'import .*PostgREST\.' src main \
+            | sed -E \
+                -e 's|/|\.|g' \
+                -e 's/(src|main)\.(.*)\.hs:import .*(PostgREST\.\S+)( .*)?/"\2" -> "\3"/'
+        )
+
+        labels=$(
+          grep -rE '^(--)?\s*Description\s*:' src main \
+            | sed -E \
+                -e 's|/|\.|g' \
+                -e 's/^(src|main)\.(.*)\.hs:(--)?\s*Description\s*:\s*(.*)$/"\2" [label="\2\\n\4"]/'
+        )
+
+        cat <<EOF | ${graphviz}/bin/dot -Tpng > imports.png
+          digraph {
+            $imports
+            $labels
+          }
+        EOF
+      '';
 in
 buildEnv {
   name = "postgrest-devtools";
@@ -106,5 +142,6 @@ buildEnv {
     run.bin
     clean.bin
     check.bin
+    importsgraph.bin
   ];
 }